* [PATCH] io_uring: comment on kfree(iovec) checks
@ 2020-08-20 8:34 Pavel Begunkov
2020-08-20 11:50 ` Jens Axboe
0 siblings, 1 reply; 2+ messages in thread
From: Pavel Begunkov @ 2020-08-20 8:34 UTC (permalink / raw)
To: Jens Axboe, io-uring
kfree() handles NULL pointers well, but io_{read,write}() checks it
because of performance reasons. Leave a comment there for those who are
tempted to patch it.
Signed-off-by: Pavel Begunkov <[email protected]>
---
fs/io_uring.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 938112826dd1..ea2d1cb5c422 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -3204,6 +3204,7 @@ static int io_read(struct io_kiocb *req, bool force_nonblock,
kiocb_done(kiocb, ret, cs);
ret = 0;
out_free:
+ /* it's reportedly faster than delegating the null check to kfree() */
if (iovec)
kfree(iovec);
return ret;
@@ -3300,6 +3301,7 @@ static int io_write(struct io_kiocb *req, bool force_nonblock,
return -EAGAIN;
}
out_free:
+ /* it's reportedly faster than delegating the null check to kfree() */
if (iovec)
kfree(iovec);
return ret;
--
2.24.0
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2020-08-20 11:50 ` Jens Axboe
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